The present invention relates to a system for automatically dimming vehicle high beam headlamps.
Regulations set forth by the United States Department of Transportation (DOT) regulate the light emissions of vehicle high beam headlamps. Various state regulations are used to control the amount of glare experienced by drivers of other vehicles whether the vehicle is traveling in the same direction as the controlled vehicle or in an opposite direction.
Known vehicle high beam headlamp emissions in accordance with the DOT regulations provide an intensity of 40,000 cd at 0 degrees, 10,000 cd at 3 degrees, 3250 cd at 6 degrees, 1500 cd at 9 degrees, and 750 cd at 12 degrees. An example of such an emission pattern is illustrated in FIG. 1. In order to avoid an illuminance of 0.5 foot candles (fc) incident on another vehicle, the vehicle high beam headlamps should be dimmed within 230 feet of another vehicle at 0 degrees, 115 feet of another vehicle at a horizontal position of 3 degrees relative to the datum, and 65 feet in the position of the other vehicle is 6 degrees relative to the controlled vehicle.
Various known head light dimmer control systems are known in the art. In order to prevent the drivers of other vehicles from being subjected to excessive glare levels, such automatic headlamp dimmer systems must sense both the head lights as well as the tail lights of other vehicles. While many known systems are adequately able to detect headlamps of oncoming vehicles, such systems are known to inadequately sense tail lights of vehicles traveling ahead of the control vehicle. As such, such systems are not able to automatically dim the high beam headlamps in time to prevent drivers of the vehicles travelling in the same direction as the controlled vehicle being subjected to excessive glare levels.
U.S. Pat. No. 5,537,003, assigned to the same assignee of the present invention, discloses an automatic headlamp dimming system which includes an optical system for sensing tail lamps as well as headlamps. The ""003 patent discloses a single photo diode with a mechanical scanning arrangement for scanning a predetermined field of view. Although the system provides relatively suitable sensing of headlamps as well as tail lamps, the optical subsystem is rather complicated and expensive to manufacture.
It is an object of the present invention to solve various problems in the prior art.
It is yet another object of the present invention to provide a vehicle headlamp dimming system which eliminates the need for mechanical optical scanning systems.
It is yet another object of the present invention to provide a headlamp dimming system that is adapted to dim the high beam head lights at different distances as a function of the horizontal angular position of another vehicle relative to the controlled vehicle.
Briefly, the present invention relates to an automatic vehicle headlamp dimming system. The system includes an optical system and an imaging processing system. The optical system is configured to discriminate between headlamps and tail lamps and focus the light rays from the headlamps and tail lamps on different portions of a pixel sensor array. The optical system, as well as the image processing system, provides for relatively increased discrimination of headlamps and tail lamps of other vehicles and also enables the high beam headlamps of the control vehicle to be controlled as a function of the distance as well as the horizontal angular position of other vehicles relative to the controlled vehicle.
These and other features, advantages, and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings.